But Casey, 35, said he was "fitter" and more motivated this time because he was doing it for a cause.

All money raised will go to Cure Kids, which funds vital medical research to find cures for life-threatening illnesses affecting children.

"I did it 10 years ago and I failed...but I really want to get there because this time we've got really nice emails and stuff from a lot of the Cure Kids people, and families who really need the money," Casey said.

About one in 30 children in New Zealand lives with a life-threatening illness or genetic malformation.

Eva Mitchell, 6, a Cure Kids ambassador, has been fighting to survive her whole life.

She was born with only half a diaphragm, meaning nothing was holding her vital organs in place.